In a conventional control operation device using a feed-forward signal, PID control is performed so that a position feed-forward signal and a position detection value coincide with each other and that a speed feed-forward signal and a speed detection value coincide with each other. (see, e.g., Japanese Patent No. 3,214,270 (JP '270))
FIG. 7 is a block diagram showing a structure of a conventional motor control system for controlling a position, etc., of a motor. In this figure, the reference numeral “1” denotes an electric motor for driving machinery as a load, “2” denotes a torque transmission mechanism connected to the electric motor 1, “3” denotes load machinery to be driven by the electric motor 1 connected to the torque-transmission mechanism 2, “19” denotes a position and speed detector which detects an actual speed and an actual position of the electric motor 1 and outputs an actual speed signal ωM and an actual position signal θM, and “5” denotes a torque control circuit.
A subtracter 24 subtracts a first simulated position signal θA1 from a position command signal θM*, and outputs the obtained error signal (θM*−θA1) to the first position control circuit 25. The first position control circuit 25 outputs a first speed signal ω1* to a subtracter 26 so as to decrease the error signal (θM*−θA1) to control so that θA1 follows θM*. The subtracter 26 subtracts a first simulated speed signal ωA1 from the first speed signal ω1* which is an output of the first position control circuit 25, and outputs the obtained error signal (ω1*−ωA1) to a first speed control circuit 16. The first speed control circuit 16 inputs the error signal (ω1*−ωA1) to control so that the error signal (ω1*−ωA1) decreases, and outputs a first torque signal T1* to a subtracter 15. The subtracter 15 subtracts an output Tc of a compensating torque operational circuit 14 from the first torque signal T1*, and outputs the obtained third torque signal T3* to an adder 6 and a subtracter 18. The subtracter 18 subtracts a simulated transfer torque signal TF which is an output of the torque transmission mechanism simulated circuit 10 from the third torque signal T3*, and outputs the obtained error signal (T3*−TF) to an electric motor simulated circuit 27. The electric motor simulated circuit 27 simulates the transfer function of the electric motor 1, inputs (T3*−TF), outputs a first simulated position signal θA1 to a subtracter 20 and the subtracter 24, and further outputs a first simulated speed signal ωA1 to a subtracter 11, a subtracter 12 and a subtracter 22. The subtracter 11 subtracts a second simulated speed signal ωA2 from the first simulated speed signal ωA1, and outputs the obtained error signal (ωA1−ωA2) to the torque transmission mechanism simulated circuit 10. The torque transmission mechanism simulated circuit 10 simulates the transfer function of the torque transmission mechanism 2, inputs the error signal (ωA1−ωA2), and outputs a simulated transfer torque signal TF to the load machinery simulated circuit 9 and the subtracter 18. The load machinery simulated circuit 9 simulates the transfer function of the load machinery 3, inputs the torque signal TF, and outputs the second simulated speed signal ωA2 to the subtracter 11 and the subtractor 12. The subtracter 12 subtracts the second simulated speed signal ωA2 from the first simulated speed signal ωA1, and outputs the obtained error signal (ωA1−ωA2) to a compensating torque operational circuit 14. The compensating torque operational circuit 14 inputs the error signal (ωA1−ωA2), and outputs a compensating torque signal TC to the subtracter 15 so that the load machinery follows the speed command signal ωM*. The subtracter 20 subtracts an actual position signal θM from the first position signal θA1, and outputs the obtained error signal (θA1−θM) to a second position control circuit 21. The second position control circuit 21 outputs the speed signal ω2* to the adder 22 so that the error signal (θA1−θM) decreases to control so that θM follows θA1. The adder 22 adds the first speed signal ωA1 and a second speed signal ω2* and outputs to a subtracter 23. The subtracter 23 subtracts the actual speed signal ωM from an output of the adder 22, and outputs the obtained error signal (ω2*+ωA1−ωM) to a second speed control circuit 8. The second speed control circuit 8 outputs a second torque signal T2* to the adder 6 so that the velocity error (ωA1−ωM) decreases to control so that the actual speed signal ωM follows the first simulated speed signal ωA1. The adder 6 adds the third torque signal T3* and the second torque signal T2*, and outputs the obtained torque command signal TM* to the torque control circuit 5. The torque control circuit 5 inputs a torque command signal TM* to drive the electric motor 1. The electric motor 1 drives the load mechanism 3 via the torque transmission mechanism 2. Moreover, the electric motor 1 is provided with a position and speed detector 19 for detecting the actual speed and the actual position of the electric motor 1 to output the actual speed signal ωM and the actual position signal θM.
FIG. 8 is a block diagram explaining a second speed control circuit 8. In this diagram, the speed control circuit 8 includes a coefficient multiplier 108 having a proportional gain KV2 and an integrator 109 having an integral gain Ki2. When the velocity error signal (ωA1−ωM) is inputted, proportional plus integral control is performed to output a torque signal T2*. Therefore, even if disturbance torque is added, it can be controlled so that the speed ωM of the electric motor 1 follows the first simulated speed signal ωA1. As mentioned above, since it is controlled so that the ωA1 follows ωM* by the first speed control circuit 16, the speed ωM of the electric motor 1 is finally controlled so as to follow the speed command signal ωM*.
FIG. 9 is a block diagram explaining the second position control circuit 21. In this diagram, the coefficient multiplier 202 having a gain KP2 performs proportional amplification of the position error (θA1−θM), and outputs a second speed signal ω2*. Since it is controlled such that θA1 follows θM*, the position θM of the electric motor 1 is controlled so as to finally follow the position command signal θM*.
In this way, a conventional control operation device performs PID control based on the error signal of the feed-forward signal θA1 and ωA1 and the detection value θM and ωM to attenuate the impact of errors of a feed-forward model or unknown disturbance torques.
In a conventional control operation device, PID control is performed, and adjustment is only performed by three control parameter values of a proportional gain Kp (KP2 in a conventional case) of a feedback position loop, a proportional gain Kv (KV2 in a conventional case) of a speed loop, and an integral gain Ki (Ki2 in a conventional case). Therefore, there was a drawback that disturbance characteristics cannot be finely adjusted to decrease influences by modeling errors and/or disturbances.
Moreover, for example, if control such as predictive control, which demonstrates an effect by the balance of feed-forward control and feedback control, is used to improve the disturbance characteristic, there was also a problem that the use of such control causes a deterioration of the control performance.
The present invention was made in view of such problems, and aims to provide a control operation device capable of finely adjusting the disturbance characteristic which attenuates the impact of a modeling error and/or a disturbance even in cases where a feed-forward model has an error to an actual controlled object or there was an unknown disturbance which was not considered in a model, and also capable of applying control such as predictive control which demonstrates an effect by the balance of feedback control to improve command following capability.